The Intel Running Average Power Limit (RAPL) technology provides platform
software with the ability to monitor, control, and get notifications on
power usage.

This feature is present in all Sandy Bridge and later Intel processors.
Newer models allow more fine grained controls to be applied.  In RAPL,
power control is divided into domains, which include package, DRAM
controller, CPU core (Power Plane 0), graphics uncore (power plane 1), etc.

The purpose of this driver is to expose the RAPL settings to userspace.
Overall, RAPL fits in the new powercap class driver in that platform
level power capping controls are exposed via this generic interface.

This driver is based on an earlier patch from Zhang Rui.

However, while the previous work was mainly focused on thermal monitoring
the focus here is on the usability from user space perspective.

References: https://lkml.org/lkml/2011/5/26/93Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Adding BIT(x) equivalent for unsigned long long type, BIT_ULL(x). Also
added BIT_ULL_MASK and BIT_ULL_WORD.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Having 64-bit MSR access methods on given CPU can avoid shifting and
simplify MSR content manipulation. We already have other combinations
of rdmsrl_xxx and wrmsrl_xxx but missing the _on_cpu version.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Added changes to Makefile and Kconfig to include in driver build.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The power capping framework providing a consistent interface between the
kernel and user space that allows power capping drivers to expose their
settings to user space in a uniform way.
The overall design of the framework is described in the documentation
added by the previous patch in this series.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Added power cap framework documentation. This explains the use of power
capping framework, sysfs and programming interface.

There are two documents:
 - Documentation/power/powercap/powercap.txt : Explains use case and APIs.
 - Documentation/ABI/testing/sysfs-class-powercap: Explains ABIs.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull watchdog fixes from Wim Van Sebroeck:
 "This will fix a deadlock on the ts72xx_wdt driver, fix bitmasks in the
  kempld_wdt driver and fix a section mismatch in the sunxi_wdt driver"

* git://www.linux-watchdog.org/linux-watchdog:
  watchdog: sunxi: Fix section mismatch
  watchdog: kempld_wdt: Fix bit mask definition
  watchdog: ts72xx_wdt: locking bug in ioctl

This driver has a section mismatch, for probe and remove functions,
leading to the following warning during the compilation.

WARNING: drivers/watchdog/built-in.o(.data+0x24): Section mismatch in
reference from the variable sunxi_wdt_driver to the function
.init.text:sunxi_wdt_probe()
The variable sunxi_wdt_driver references
the function __init sunxi_wdt_probe()
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

STAGE_CFG bits are defined as [5:4] bits. However, '(((x) & 0x30) << 4)'
handles [9:8] bits. Thus, it should be fixed in order to handle
[5:4] bits.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Calling the WDIOC_GETSTATUS & WDIOC_GETBOOTSTATUS and twice will cause a
interruptible deadlock.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Pull ARM SoC fixes from Olof Johansson:
 "A small batch of fixes this week, mostly OMAP related.  Nothing stands
  out as particularly controversial.

  Also a fix for a 3.12-rc1 timer regression for Exynos platforms,
  including the Chromebooks"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: exynos: dts: Update 5250 arch timer node with clock frequency
  ARM: OMAP2: RX-51: Add missing max_current to rx51_lp5523_led_config
  ARM: mach-omap2: board-generic: fix undefined symbol
  ARM: dts: Fix pinctrl mask for omap3
  ARM: OMAP3: Fix hardware detection for omap3630 when booted with device tree
  ARM: OMAP2: gpmc-onenand: fix sync mode setup with DT

Without the "clock-frequency" property in arch timer node, could able
to see the below crash dump.

[<c0014e28>] (unwind_backtrace+0x0/0xf4) from [<c0011808>] (show_stack+0x10/0x14)
[<c0011808>] (show_stack+0x10/0x14) from [<c036ac1c>] (dump_stack+0x7c/0xb0)
[<c036ac1c>] (dump_stack+0x7c/0xb0) from [<c01ab760>] (Ldiv0_64+0x8/0x18)
[<c01ab760>] (Ldiv0_64+0x8/0x18) from [<c0062f60>] (clockevents_config.part.2+0x1c/0x74)
[<c0062f60>] (clockevents_config.part.2+0x1c/0x74) from [<c0062fd8>] (clockevents_config_and_register+0x20/0x2c)
[<c0062fd8>] (clockevents_config_and_register+0x20/0x2c) from [<c02b8e8c>] (arch_timer_setup+0xa8/0x134)
[<c02b8e8c>] (arch_timer_setup+0xa8/0x134) from [<c04b47b4>] (arch_timer_init+0x1f4/0x24c)
[<c04b47b4>] (arch_timer_init+0x1f4/0x24c) from [<c04b40d8>] (clocksource_of_init+0x34/0x58)
[<c04b40d8>] (clocksource_of_init+0x34/0x58) from [<c049ed8c>] (time_init+0x20/0x2c)
[<c049ed8c>] (time_init+0x20/0x2c) from [<c049b95c>] (start_kernel+0x1e0/0x39c)

THis is because the Exynos u-boot, for example on the Chromebooks, doesn't set
up the CNTFRQ register as expected by arch_timer. Instead, we have to specify
the frequency in the device tree like this.
Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
[olof: Changed subject, added comment, elaborated on commit message]
Signed-off-by: Olof Johansson <olof@lixom.net>

Merge tag 'fixes-against-v3.12-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes

From Tony Lindgren:

Few fixes for omap3 related hangs and errors that people have
noticed now that people are actually using the device tree
based booting for omap3.

Also one regression fix for timer compile for dra7xx when
omap5 is not selected, and a LED regression fix for n900.

* tag 'fixes-against-v3.12-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: OMAP2: RX-51: Add missing max_current to rx51_lp5523_led_config
  ARM: mach-omap2: board-generic: fix undefined symbol
  ARM: dts: Fix pinctrl mask for omap3
  ARM: OMAP3: Fix hardware detection for omap3630 when booted with device tree
  ARM: OMAP2: gpmc-onenand: fix sync mode setup with DT
Signed-off-by: Olof Johansson <olof@lixom.net>

Pull parisc fixes from Helge Deller:
 "This patchset includes a bugfix to prevent a kernel crash when memory
  in page zero is accessed by the kernel itself, e.g.  via
  probe_kernel_read().

  Furthermore we now export flush_cache_page() which is needed
  (indirectly) by the lustre filesystem.  The other patches remove
  unused functions and optimizes the page fault handler to only evaluate
  variables if needed, which again protects against possible kernel
  crashes"

* 'parisc-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: let probe_kernel_read() capture access to page zero
  parisc: optimize variable initialization in do_page_fault
  parisc: fix interruption handler to respect pagefault_disable()
  parisc: mark parisc_terminate() noreturn and cold.
  parisc: remove unused syscall_ipi() function.
  parisc: kill SMP single function call interrupt
  parisc: Export flush_cache_page() (needed by lustre)

Pull slave-dmaengine fixes from Vinod Koul:
 "Another week, time to send another fixes request taking time out of
  extended weekend for the festivities in this part of the world.

  We have two fixes from Sergei for rcar driver and one fixing memory
  leak of edma driver by Geyslan"

* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
  dma: edma.c: remove edma_desc leakage
  rcar-hpbdma: add parameter to set_slave() method
  rcar-hpbdma: remove shdma_free_irq() calls

Signed-off-by: Helge Deller <deller@gmx.de>

The attached change defers the initialization of the variables tsk, mm
and flags until they are needed. As a result, the code won't crash if a
kernel probe is done with a corrupt context and the code will be better
optimized.
Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

Running an "echo t > /proc/sysrq-trigger" crashes the parisc kernel.  The
problem is, that in print_worker_info() we try to read the workqueue info via
the probe_kernel_read() functions which use pagefault_disable() to avoid
crashes like this:
    probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
    probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
    probe_kernel_read(name, wq->name, sizeof(name) - 1);

The problem here is, that the first probe_kernel_read(&pwq) might return zero
in pwq and as such the following probe_kernel_reads() try to access contents of
the page zero which is read protected and generate a kernel segfault.

With this patch we fix the interruption handler to call parisc_terminate()
directly only if pagefault_disable() was not called (in which case
preempt_count()==0).  Otherwise we hand over to the pagefault handler which
will try to look up the faulting address in the fixup tables.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v3.0+
Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

Signed-off-by: Helge Deller <deller@gmx.de>

Signed-off-by: Helge Deller <deller@gmx.de>

Commit 9a46ad6d "smp: make smp_call_function_many() use logic
similar to smp_call_function_single()" has unified the way to handle
single and multiple cross-CPU function calls. Now only one interrupt
is needed for architecture specific code to support generic SMP function
call interfaces, so kill the redundant single function call interrupt.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>

ERROR: "flush_cache_page" [drivers/staging/lustre/lustre/libcfs/libcfs.ko] undefined!
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Helge Deller <deller@gmx.de>

Olga reported that file descriptors opened with O_PATH do not work with
fstatfs(), found during further development of ksh93's thread support.

There is no reason to not allow O_PATH file descriptors here (fstatfs is
very much a path operation), so use "fdget_raw()".  See commit
55815f70 ("vfs: make O_PATH file descriptors usable for 'fstat()'")
for a very similar issue reported for fstat() by the same team.
Reported-and-tested-by: ольга крыжановская <olga.kryzhanovska@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org	# O_PATH introduced in 3.0+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull ext4 bugfixes from Ted Ts'o:
 "A bug fix and performance regression fix for ext4"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix memory leak in xattr
  ext4: fix performance regression in writeback of random writes

Pull btrfs fixes from Chris Mason:
 "We've got more bug fixes in my for-linus branch:

  One of these fixes another corner of the compression oops from last
  time.  Miao nailed down some problems with concurrent snapshot
  deletion and drive balancing.

  I kept out one of his patches for more testing, but these are all
  stable"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix oops caused by the space balance and dead roots
  Btrfs: insert orphan roots into fs radix tree
  Btrfs: limit delalloc pages outside of find_delalloc_range
  Btrfs: use right root when checking for hash collision

Pull sound fixes from Takashi Iwai:
 "All stable fixes except for a trivial headset mic fixup: the removal
  of bogus frame checks in snd-usb-usx2y driver that have regressed in
  the recent kernel versions, the HD-audio HDMI channel map fix, and a
  few HD-audio device-specific fixes"

* tag 'sound-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Sony VAIO Pro 13 (haswell) now has a working headset jack
  ALSA: hda - Add a headset mic model for ALC269 and friends
  ALSA: hda - Fix microphone for Sony VAIO Pro 13 (Haswell model)
  ALSA: hda - Add fixup for ASUS N56VZ
  ALSA: hda - hdmi: Fix channel map switch not taking effect
  ALSA: hda - Fix mono speakers and headset mic on Dell Vostro 5470
  ALSA: snd-usb-usx2y: remove bogus frame checks

Pull i2c fixes from Wolfram Sang:
 "We had various reports of problems with deferred probing in the I2C
  subsystem, so this pull requst is a little bigger than usual.

  Most issues should be addressed now so devices will be found
  correctly.  A few ususal driver bugfixes are in here, too"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: i2c-mux-pinctrl: use deferred probe when adapter not found
  i2c: i2c-arb-gpio-challenge: use deferred probe when adapter not found
  i2c: i2c-mux-gpio: use deferred probing
  i2c: i2c-mux-gpio: don't ignore of_get_named_gpio errors
  i2c: omap: Clear ARDY bit twice
  i2c: Not all adapters have a parent
  i2c: i2c-stu300: replace platform_driver_probe to support deferred probing
  i2c: i2c-mxs: replace platform_driver_probe to support deferred probing
  i2c: i2c-imx: replace platform_driver_probe to support deferred probing
  i2c: i2c-designware-platdrv: replace platform_driver_probe to support deferred probing

If we take the 2nd retry path in ext4_expand_extra_isize_ea, we
potentionally return from the function without having freed these
allocations.  If we don't do the return, we over-write the previous
allocation pointers, so we leak either way.

Spotted with Coverity.

[ Fixed by tytso to set is and bs to NULL after freeing these
  pointers, in case in the retry loop we later end up triggering an
  error causing a jump to cleanup, at which point we could have a double
  free bug. -- Ted ]
Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@vger.kernel.org

Pull gcc "asm goto" miscompilation workaround from Ingo Molnar:
 "This is the fix for the GCC miscompilation discussed in the following
  lkml thread:

    [x86] BUG: unable to handle kernel paging request at 00740060

  The bug in GCC has been fixed by Jakub and the fix will be part of the
  GCC 4.8.2 release expected to be released next week - so the quirk's
  version test checks for <= 4.8.1.

  The quirk is only added to compiler-gcc4.h and not to the higher level
  compiler.h because all asm goto uses are behind a feature check"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  compiler/gcc4: Add quirk for 'asm goto' miscompilation bug

Pull x86 fixes from Ingo Molnar:
 "A build fix and a reboot quirk"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/reboot: Add reboot quirk for Dell Latitude E5410
  x86, build, pci: Fix PCI_MSI build on !SMP

Pull ARC fix from Vineet Gupta:
 "Fix for broken gdb 'jump'"

* tag 'arc-fixes-for-3.12-part3' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc"

ARCompact TRAP_S insn used for breakpoints, commits before exception is
taken (updating architectural PC). So ptregs->ret contains next-PC and
not the breakpoint PC itself. This is different from other restartable
exceptions such as TLB Miss where ptregs->ret has exact faulting PC.
gdb needs to know exact-PC hence ARC ptrace GETREGSET provides for
@stop_pc which returns ptregs->ret vs. EFA depending on the
situation.

However, writing stop_pc (SETREGSET request), which updates ptregs->ret
doesn't makes sense stop_pc doesn't always correspond to that reg as
described above.

This was not an issue so far since user_regs->ret / user_regs->stop_pc
had same value and both writing to ptregs->ret was OK, needless, but NOT
broken, hence not observed.

With gdb "jump", they diverge, and user_regs->ret updating ptregs is
overwritten immediately with stop_pc, which this patch fixes.
Reported-by: Anton Kolesov <akolesov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Pull MIPS fix from Ralf Baechle:
 "Just one fix.  The stack protector was loading the value of the canary
  instead of its address"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: stack protector: Fix per-task canary switch

Pull drm fixes from Dave Airlie:
 "All over the map..

   - nouveau:
     disable MSI, needs more work, will try again next merge window
   - radeon:
      audio + uvd regression fixes, dpm fixes, reset fixes
   - i915:
     the dpms fix might fix your haswell

  And one pain in the ass revert, so we have VGA arbitration that when
  implemented 4-5 years ago really hoped that GPUs could remove
  themselves from arbitration completely once they had a kernel driver.

  It seems Intel hw designers decided that was too nice a facility to
  allow us to have so they removed it when they went on-die (so since
  Ironlake at least).  Now Alex Williamson added support for VGA
  arbitration for newer GPUs however this now exposes itself to
  userspace as requireing arbitration of GPU VGA regions and the X
  server gets involved and disables things that it can't handle when VGA
  access is possibly required around every operation.

  So in order to not break userspace we just reverted things back to the
  old known broken status so maybe we can try and design out way out.

  Ville also had a patch to use stop machine for the two times Intel
  needs to access VGA space, that might be acceptable with some rework,
  but for now myself and Daniel agreed to just go back"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (23 commits)
  Revert "i915: Update VGA arbiter support for newer devices"
  Revert "drm/i915: Delay disabling of VGA memory until vgacon->fbcon handoff is done"
  drm/radeon: re-enable sw ACR support on pre-DCE4
  drm/radeon/dpm: disable bapm on TN asics
  drm/radeon: improve soft reset on CIK
  drm/radeon: improve soft reset on SI
  drm/radeon/dpm: off by one in si_set_mc_special_registers()
  drm/radeon/dpm/btc: off by one in btc_set_mc_special_registers()
  drm/radeon: forever loop on error in radeon_do_test_moves()
  drm/radeon: fix hw contexts for SUMO2 asics
  drm/radeon: fix typo in CP DMA register headers
  drm/radeon/dpm: disable multiple UVD states
  drm/radeon: use hw generated CTS/N values for audio
  drm/radeon: fix N/CTS clock matching for audio
  drm/radeon: use 64-bit math to calculate CTS values for audio (v2)
  drm/edid: catch kmalloc failure in drm_edid_to_speaker_allocation
  Revert "drm/fb-helper: don't sleep for screen unblank when an oops is in progress"
  drm/gma500: fix things after get/put page helpers
  drm/nouveau/mc: disable msi support by default, it's busted in tons of places
  drm/i915: Only apply DPMS to the encoder if enabled
  ...

Just got the positive confirmation from a tester:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1227093/comments/28Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Using the headset mic model will cause the headset mic to be labeled
"headset mic" instead of just "mic".
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

The external mic showed up with a precense detect of "always present",
essentially disabling the internal mic. Therefore turn off presence
detection for this pin.

Note: The external mic seems not yet working, but an internal mic is
certainly better than no mic at all.

Cc: stable@vger.kernel.org
BugLink: https://bugs.launchpad.net/bugs/1227093Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down
a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto'
constructs, as outlined here:

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670

Implement a workaround suggested by Jakub Jelinek.
Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

This reverts commit 81b5c7bc.

Adding drm/i915 into the vga arbiter chain means that X (in a piece of
well-meant paranoia) will do a get/put on the vga decoding around
_every_ accel call down into the ddx. Which results in some nice
performance disasters [1]. This really breaks userspace, by disabling
DRI for everyone, and stops OpenGL from working, this isn't limited
to just the i915 but both the integrated and discrete GPUs on
multi-gpu systems, in other words this causes untold worlds of pain,

Ville tried to come up with a Great Hack to fiddle the required VGA
I/O ops behind everyone's back using stop_machine, but that didn't
really work out [2]. Given that we're fairly late in the -rc stage for
such games let's just revert this all.

One thing we might want to keep is to delay the disabling of the vga
decoding until the fbdev emulation and the fbcon screen is set up. If
we kill vga mem decoding beforehand fbcon can end up with a white
square in the top-left corner it tried to save from the vga memory for
a seamless transition. And we have bug reports on older platforms
which seem to match these symptoms.

But again that's something to play around with in -next.

References: [1] http://lists.x.org/archives/xorg-devel/2013-September/037763.html
References: [2] http://www.spinics.net/lists/intel-gfx/msg34062.html
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>